Postural Reflexes

Overview

• Automatic movements controlling equilibration.
• Combat gravity effects during upright posture and movement.
• Origin: Higher centers including Midbrain, Basal Ganglia, and Cortex.
• Pattern: Appear during infancy; persist throughout life.
• Differentiates from primitive reflexes (present at birth, disappear over time).
• Function: Provide basis for voluntary movement, posture, and balance.

Classification and Timeline

Broadly classified into three groups based on function and chronological appearance.

Foundational Assessment: Postural Tone

Postural tone creates the required resistance to passive movement, serving as the prerequisite for postural reflexes.

• Traction Response: Pull infant to sitting position. Normal term infant shows slight head lag, then head falls forward. Severe lag indicates hypotonia.
• Vertical Suspension: Hold infant by axillae. Normal infant remains suspended with flexed lower extremities. Hypotonic infant slips through hands.
• Horizontal (Ventral) Suspension: Hold infant prone over hand. Normal infant raises head and flexes limbs. Hypotonic infant drapes over hand forming an inverted "U" shape.

Righting Reflexes

• Level of Control: Midbrain.
• Role: Maintain head in vertical position; align body segments.

Labyrinthine and Optical Righting

• Test: Blindfold child (Labyrinthine) or keep eyes open (Optical); suspend vertically and tilt.
• Response: Head orients to vertical axis.
• Timeline: Emerges 2–4 months.
• Significance:
  • Correlates directly with acquisition of head control.
  • Delay indicates general developmental delay or marked hypotonia.

Landau Reflex

• Test: Suspend infant horizontally in prone position.
• Response: Extension of head, trunk, and hips ("Airplane posture").
• Timeline: Appears 3 months; peaks 6–8 months; disappears 12–24 months.
• Diagnostic Significance:
  • Hypotonia: Infant collapses into inverted "U" shape (Classic Approach to a floppy infant sign).
  • Hypertonia/Spasticity: Excessive extension or lower extremity scissoring.
  • Absence: Strong indicator of motor dysfunction (e.g., Cerebral Palsy).
  • Prognostication: Favorable prognostic sign for eventual standing.

Body-on-Body (BOB) and Neck-on-Body (NOB)

• Test: Rotate head to one side (NOB) or rotate hips (BOB).
• Response by Age:
  • Immature (0–4 months): Log rolling (body turns as a solid block).
  • Mature (6+ months): Segmental rolling (shoulders rotate, then pelvis follows).
• Significance: Segmental rolling indicates cortical maturation and ability to dissociate body parts. Essential prerequisite for crawling and walking.

Protective / Parachute Reactions

• Level of Control: Cortical.
• Trigger: Body displacement shifting center of gravity outside base of support.

Anterior Parachute

• Test: Suddenly thrust infant downwards towards surface while holding waist.
• Response: Extension of arms and opening of hands to break the fall.
• Timeline: Appears 6–8 months; fully developed 10–11 months; persists throughout life.
• Diagnostic Significance:
  • Asymmetry: Most sensitive sign for mild Hemiplegia. Affected arm extends slowly, fails to extend, or extends with fisted hand.
  • Absence: Indicates severe quadriparesis or severe cognitive delay. Also signals delayed walking.

Lateral and Posterior Propping

• Test: Displace body to shift center of gravity outside base of support.
• Response: Observe for spontaneous arm extension and propping to prevent falling.
• Timeline: Lateral appears 7 months; Posterior appears 9 months.
• Diagnostic Significance:
  • Determines readiness for independent sitting.
  • Child cannot sit safely unassisted until lateral propping is established (Tripod sitting).
  • Posterior propping allows child to pivot safely while sitting.

Equilibrium Reactions

• Level of Control: Cortical.
• Trigger: Subtle adjustments of trunk tone to maintain balance during supporting surface tilt.
• Test: Tilt child on rocker board or bed.
• Response: Curving of trunk against the tilt; extension of extremities on the uphill side to shift center of gravity back.
• Diagnostic Significance:
  • Absolute prerequisite for standing and walking.
  • Motor Discrepancy: Child exhibiting righting and protective reflexes but lacking equilibrium reactions may stand but will suffer frequent falls.

Clinical Utility and Diagnostics

Early Diagnosis of Cerebral Palsy (CP)

• Diagnosis relies heavily on the "Motor Quotient" (interplay of primitive vs. postural reflexes).
• Classic CP Pattern: Retention of Primitive Reflexes (e.g., ATNR, Moro) combined with Delayed or Absent Postural Reflexes.
• Clinical Example: 9-month-old infant with persistent Moro reflex and absent Parachute reflex possesses high probability of CP.

Localization of Neurological Lesions

• Hemiparesis: Asymmetry in Parachute or Placing reactions.
• Midbrain Damage: Absent Righting Reflexes.
• Cortical/Basal Ganglia Damage: Absent Equilibrium Reactions.

Neuromotor Prognostication

• Timely appearance of postural reflexes serves as a superior predictor of eventual ambulation compared to the mere disappearance of primitive reflexes.
• Presence of Landau reflex acts as a strong positive predictor for eventual standing capability.